Tables for
Volume G
Definition and exchange of crystallographic data
Edited by S. R. Hall and B. McMahon

International Tables for Crystallography (2006). Vol. G, ch. 2.4, p. 51


F. H. Allen,a* J. M. Barnard,b A. P. F. Cookb and S. R. Hallc

aCambridge Crystallographic Data Centre, 12 Union Road, Cambridge, CB2 1EZ, England,bBCI Ltd, 46 Uppergate Road, Stannington, Sheffield S6 6BX, England, and cSchool of Biomedical and Chemical Sciences, University of Western Australia, Crawley, Perth, WA 6009, Australia
Correspondence e-mail:


Query substructure for conjugated ketones or thioketones. Atom C1 is sp3 hybridized (total number of attached hydrogen and non-hydrogen atoms = 4) and carries at least one hydrogen atom. Bond C3—C4 may be localized double (D), aromatic (A) or delocalized double (E) in CCDC conventions.